Diverse Carotenoid Functions in Photoresponse in Euglena gracilis

Abstract

Carotenoids are hydrophobic pigment molecules that enrich human lifestyle through using as foods, cosmetics, and pharmaceuticals. Carotenoids themselves are biosynthesized in photosynthetic organisms such as plants and algae, and have various photo-related functions involved in photosynthesis and photoprotection. In particular, microalgae such as euglenophytes, diatoms, and dinoflagellates established by secondary endosymbiosis of red alga biosynthesize a wide variety of carotenoids (ex. diadinoxanthin) that are absent in land plants or green algae. On the other hand, carotenoid biosynthesis and physiological functions in photoresponse in such algae has not yet been elucidated. This review focuses on the Euglena gracilis studied remarkably for industrial use among secondary endosymbiotic algae, and we introduce recent progress in carotenoid biosynthetic pathway and carotenoid-mediated photoresponses in E. gracilis.

graphical abstract